They were, but were beaten to it because KT had £4m ring fenced to finished the stand and signed an MoU to that effect.
You can reverse engineer the value KT and DB need £10m to break even so do the council the rest will be split (another bone of contention). Cardoza was offered £27m for the land back in 2014 and that was massively under price.
I personally know the guy that did the soil sampling on virtually all of the site. I have worked with him on several projects. Whilst I don’t doubt the value has increased, I really can’t see a substantial amount more based on what I have been told. There has to be a huge cost in venting, ground work and prep before anything starts. Having said that, it doesn’t really matter, if what you put on it is making good money.